Measure complete Trace constructor parity and decode reduction

[realmarcin]

The native parsing correction in #4537 lacked a complete-constructor comparison against the same full-schema inputs. Add a bounded offline driver comparing literal baseline 0125 and reviewed candidate a8c11973 on the unchanged preparation05 captured streams. Both versions load their exact three modules under canonical identities; constructor timing is separated from complete state/method checks and decode instrumentation.

Actual result: all six constructors returned identical complete typed evidence. Both external payloads retain the same 32,722,082 uncompressed bytes. All six refusal controls, two instance checks and four exact/wrong-command advance checks passed; full-stream decodes fall from two to one per stream. The observed three-sample CPU medians were 0.101295041s baseline and 0.054824542s candidate. Every sample and fixed order are disclosed, including much slower first samples; this is constructor-only evidence, not a generalized speedup, callback fraction or native acceptance result.

The worker completed in 19.36 seconds under its fixed 120-second bound. It starts no native/helper/provider executable, preserves all captured inputs and publishes only to a new disjoint output. Full payloads remain external with compact hashes/timings committed in notes/native_trace_comparison_2026-10-08/.

Validation: 184 comparison/retained-utility tests and 90 production-candidate tests passed. Independent reviews filed and resolved closed-evidence, post-EOF deadline, current-advance coverage and metadata-mutation findings. Final independent inspection verified full payload equality, control graphs, all 68 current case files, 9,214 baseline source files, 83 historical bytes, selected modules/runtime, 17 documented file pins and both JUnit records.

#4537, #4354 and #4400 remain open for separate integration and acceptance. This does not reconstruct unavailable 4366 code, relabel original diagnostics or authorize a scientific/native/provider campaign. Candidate PR #4659 has separate CI/integration requirements.

Closes #4657
Closes #4658
Closes #4661
Closes #4662
Closes #4663